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    <p align="center"><img style="width:100%"
                           src="img/chadong.gif"
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    <p><font face="Arial">这个计算器计算偏置电压和电流，以及增益和频率响应。&nbsp;</font></p>
    <p alight="center">
    </p>
    <form name="ParamForm" action="" method="post">
        <table height="573" border="1" style="font-size:12px;">
            <tbody>
            <tr>
                <td><font face="Arial" size="3">R1</font></td>
                <td><font face="Arial"><input size="17" value="18" name="R1"> (KΩ)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">R2</font></td>
                <td><font face="Arial"><input size="17" value="3.9" name="R2"> (KΩ)</font></td>
            </tr>
            <tr>
                <td><font face="Arial" size="3">R<sub>C</sub>
                </font><font face="Arial" size="2">(Collector
                    resistor)集电极电阻</font></td>
                <td><font face="Arial"><input size="17" value="3" name="RC"> (KΩ)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial" size="3">R<sub>E</sub>
                </font><font face="Arial" size="2">(Emitter
                    resistor)发射极电阻</font></td>
                <td><font face="Arial"><input size="17" value="3.4" name="RE"> (KΩ)&nbsp;</font>
                </td>
            </tr>
            <tr>
                <td><font face="Arial">VP<font size="2"> (Supply
                    Voltage)电源电压</font></font></td>
                <td><font face="Arial"><input size="17" value="25" name="VP"> (V)</font></td>
            </tr>
            <tr>
                <td><font face="Arial">Beta <font size="2">(DC Current
                    Gain)直流电流增益</font></font></td>
                <td><font face="Arial"><input size="17" value="100" name="Beta"></font></td>
            </tr>
            <tr>
                <td><font face="Arial">V<sub>BE </sub><font size="2">(Base to emitter
                    drop)基极-发射极压降</font></font></td>
                <td><font face="Arial"><input size="17" value="0.6" name="VBE"> (V)</font></td>
            </tr>
            <tr>
                <td><font face="Arial">R<sub><font size="2">s</font></sub> <font size="2">(Source
                    Resistance): 电源内阻</font></font></td>
                <td><font face="Arial"><input size="17" value="50" name="RS"> (Ω)</font></td>
            </tr>
            <tr>
                <td><font face="Arial" size="3">R</font><font face="Arial"
                                                              size="2"><sub>L</sub></font><font
                        face="Arial" size="3"> </font><font face="Arial" size="2">(Load
                    resistor)负载电阻</font></td>
                <td><font face="Arial"><input size="17" value="470" name="RL"> (Ω)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">f<font face="Arial" size="1"><sub>T</sub></font> <font
                        size="2">(Current
                    Gain BW Product):电流增益带宽</font></font></td>
                <td><font face="Arial"><input size="17" value="400" name="Ft"> (MHz)</font></td>
            </tr>
            <tr>
                <td><font face="Arial">C<font size="2"><sub>CB</sub></font> <font size="2">(Cu
                    Collector-Base Cap.): 集电极与基极间电容</font></font></td>
                <td><font face="Arial"><input size="17" value="2" name="Ccb"> (pF)</font></td>
            </tr>
            <tr>
                <td><font face="Arial">C<font size="2"><sub>BE</sub></font> <font size="2">(C</font></font><b><font
                        size="2"><sub>π</sub></font></b><font size="2">,
                    Base-Emitter Cap.):</font><font face="Arial"
                                                    size="2">基极和发射极之间的电容(可选)</font><font size="2">
                    &nbsp;
                </font></td>
                <td><font face="Arial"><input size="17" name="Cbe">
                    (pF)</font></td>
            </tr>
            <tr>
                <td colspan="2">
                    <p align="center"><font face="Arial"><input
                            onclick="Compute(document.ParamForm)" type="button" value="计算"></font>
                    </p></td>
            </tr>
            <tr>
                <td><font face="Arial">V<font size="2"><sub>C</sub></font> <font size="2">(Collector
                    Voltage)集电极电压</font></font></td>
                <td><font face="Arial"><input size="17" name="VC">
                    (V)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">V<font size="2"><sub>E</sub></font></font> <font face="Arial"
                                                                                        size="2">(Emitter
                    Voltage)发射极电压</font></td>
                <td><font face="Arial"><input size="17" name="VE">
                    (V)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">V<font size="2"><sub>B</sub>
                    (Base Voltage)基极电压</font></font></td>
                <td><font face="Arial"><input size="17" name="VB">
                    (V)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">I<sub>E</sub><font size="2">
                    (Emitter Voltage)发射极电压</font></font></td>
                <td><font face="Arial"><input size="17" name="IE">
                    (mA)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">I<sub>C</sub><font size="2">
                    (Collector Voltage)集电极电压</font></font></td>
                <td><font face="Arial"><input size="17" name="IC">
                    (mA)&nbsp;</font></td>
            </tr>
            <tr>
                <td><font face="Arial">I<sub>B</sub> <font size="2">(Base Voltage)基极电压</font></font>
                </td>
                <td><font face="Arial"><input size="17" name="IB">
                    (mA)&nbsp;</font></td>
            </tr>
            <tr>
                <td>g<sub><i><font size="1">m </font></i></sub><font face="Arial">(Transconductance)跨导</font>
                </td>
                <td><font face="Arial"><input size="17" name="gm">
                </font></td>
            </tr>
            <tr>
                <td>r<b><font size="2"><sub>π</sub></font></b><font face="Arial"> <font size="2">(Input
                    Resistance of
                    BJT</font></font><font size="2"> at low
                    freq)晶体管输入阻抗,低频率的</font></td>
                <td><font face="Arial"><input size="17" name="Rpi"> (Ω)
                </font></td>
            </tr>
            <tr>
                <td>r<b><font size="2"><sub>e</sub></font></b><font face="Arial">&nbsp; </font></td>
                <td><font face="Arial"><input size="17" name="re"> (Ω)
                </font></td>
            </tr>
            <tr>
                <td>R<sub>IN</sub><font face="Arial"> <font size="2">(Input Resistance</font></font><font
                        size="2"> of Amp)放大器输入阻抗</font></td>
                <td><font face="Arial"><input size="17" name="Rin">
                    (KΩ)</font></td>
            </tr>
            <tr>
                <td colspan="2">
                    <p align="center">　</p></td>
            </tr>
            <tr>
                <td><font face="Arial">A<font size="2"> (Amplifier
                    Voltage Gain)放大器的电压增益</font></font></td>
                <td><font face="Arial"><input size="17" name="A">
                </font></td>
            </tr>
            <tr>
                <td><font face="Arial">f<font size="1"><sub>P1</sub></font></font></td>
                <td><font face="Arial"><input size="17" name="fp1">
                    (MHz)</font></td>
            </tr>
            <tr>
                <td><font face="Arial">f<font size="1"><sub>P2</sub></font></font></td>
                <td><font face="Arial"><input size="17" name="fp2">
                    (MHz)</font></td>
            </tr>
            </tbody>
        </table>
    </form>
    <h4><font face="Arial">Equations</font></h4>
    <p><font face="Arial">V<sub>B</sub>=&nbsp;
        VP*R2/(R1+R2)</font></p>
    <p><font face="Arial">V<sub>E</sub>=
        V<sub>B</sub>-V<sub>BE</sub></font></p>
    <p><font face="Arial">I<sub>E=</sub>V<sub>E</sub>/R<sub>E</sub></font></p>
    <p><font face="Arial">Alpha= Beta/(Beta+1);</font></p>
    <p><font face="Arial">I<sub>C=
    </sub>Alpha*I<sub>E</sub></font></p>
    <p><font face="Arial">V<sub>C</sub>= VP -&nbsp;
        I<sub>C</sub>*R<sub>C</sub>/2</font></p>
    <p><font face="Arial">I<sub>B</sub>=I<sub>C</sub>/Beta</font></p>
    <p>　</p>
    <p>g<i><font size="1"><sub>m </sub></font></i><font face="Arial">= Ic/25mA</font></p>
    <p>r<b><font size="2"><sub>e</sub></font></b><font face="Arial">= Alpha/</font>g<i><font
            size="1"><sub>m
    </sub></font></i></p>
    <p>r<b><font size="2"><sub>π</sub></font></b><font face="Arial">= Beta/</font>g<i><font
            size="1"><sub>m
    </sub></font></i></p>
    <p>A=<font face="Arial">Alpha*</font> r<b><font size="2"><sub>π</sub></font></b>*<font
            face="Arial" size="3">R<sub>C</sub></font>/(<font face="Arial">R<sub><font
            size="2">s</font></sub></font>+2*r<b><font size="2"><sub>π</sub></font></b>)/r<b><font
            size="2"><sub>e</sub></font></b></p>
    <p><font face="Arial">f<font size="1"><sub>P1</sub></font></font>=1/(<font size="3">2*π*(</font><font
            face="Arial">R<font size="2"><sub>s</sub></font></font>||2*r<b><font
            size="2"><sub>π</sub></font></b>)*(<font size="3">C</font><font size="2"><sub>BE/2</sub></font>+<font
            size="3">C</font><font size="2"><sub>BC</sub></font>))</p>
    <p><font face="Arial">f<font size="1"><sub>P2</sub></font></font>=1/(<font
            size="3">2*π*</font><font face="Arial" size="3">R<sub>C</sub></font><font
            size="3">*C</font><font size="2"><sub>BC</sub></font>)</p>
    <p>　</p>
    <p><font face="Arial">f<font face="Arial" size="1"><sub>T</sub></font></font><font size="3">=
    </font>g<i><font size="1"><sub>m</sub></font></i><font size="3">/(2π*(C</font><font
            size="2"><sub>BE</sub></font><font size="3">+C</font><font size="2"><sub>BC</sub></font><font
            size="3">))</font></p>
    <p><font size="3">The lower pole is
        dominate:&nbsp;</font></p>
    <p>　</p>
    <p align="center"><font size="1">. </font></p>
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